On the other end of the spectrum, Ruby blocks (and all the attached machinery) feel to me like a much nicer abstraction to work with. Go's goroutines and channels show giving a language purpose-built concurrency primitives is a really nice model (I expect Erlang would be another good example of the same, but never tried it), and the monadic approach in Haskell makes it so that you could almost directly translate node.js code and end up with something far more readable.